The present invention relates to a public telephone set, and more particularly to a public telephone set provided with a dial call originating means and having function to effect a charging or billing processing.
Hitherto, there has been known a metering system as shown in the Japanese patent preliminary publication No. 59-25546 as means for allowing a public telephone set which connects to a switching system or an exchange to which an office multi-charging signal based on the periodic pulse metering method or Carlson method is not transmitted to effect a toll call.
However, this system is configured to consider only the second digit subsequent to the first digit "0" and to select e.g. one from four kinds of timer intervals or time periods. When an attempt is made to deal with a plurality of digits and to provide a larger number of timer intervals, the circuit configuration which combines these functions becomes complicated, with the result that its realization is difficult in practice.